´strange´running problem?

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BikerChris
Posts: 1
Joined: Thu Sep 01, 2022 6:19 pm

´strange´running problem?

Post by BikerChris »

1979 BMW R65

Bike starts, idle, revs, no problem. Then i warm it up and head to a faster road. It then revs up to higher revs, then 'bogs down', and loses a lot of power. After this, it refuses to rev, and limps on. If I leave the bike to cool, we're back to the beginning....
Not even sure if it's an electrical or carb problem. Any ideas really appreciated :)
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gspd
Posts: 1041
Joined: Tue Aug 03, 2010 8:04 pm

Re: ´strange´running problem?

Post by gspd »

Could be anything.
This is impossible for anyone to diagnose with out a road test and a bit of poking around.
All suggestions would be purely speculative at this point.
The only thing I can say with confidence is that it IS fuel or ignition related.
Probably not a big deal.
Start with a basic check up/tune up and take it from there.

My shot in the dark guess, for what it's worth...
faulty condenser
Mechanic from Hell
"I remember every raging second of it...
My bike was on fire, the road was on fire, and I was on fire.
It was the best ride ever!"
Tom H Ca
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Joined: Fri Feb 04, 2011 2:56 am

Re: ´strange´running problem?

Post by Tom H Ca »

As mentioned, check the basics.

Just a thought, if it has a fuel filter on the petcocks or elsewhere, it could be clogged. Had a bike that would cut out at freeway speeds after a bit. Add on VW type fuel filter looked clean, but was for whatever reason not allowing enough fuel to flow. If I stopped and shut it off for a minute or two, it would then start and run normal, then again after a bit start cutting out.

So, if it takes just a minute, maybe fuel filter issue. If it takes a half hour or the like, maybe heat related, like an electrical component. Coils can do funny things when they go bad or with heat.

Tom
'73 R75/5
'70 Guzzi Ambo 750
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Tom
Rob Frankham
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Joined: Thu Aug 26, 2010 2:11 pm
Location: Scotland UK, 20 miles from civilisation up a dead end road!
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Re: ´strange´running problem?

Post by Rob Frankham »

This is classic for the 'chokes' being wholly or partially left on.. Are you sure they aren't sticking and not going off completely. Have you had the chokes apart and refitted them with the rotary slides backwards or swapped from side to side? There are other causes but this is the first thing I'd check...

Rob
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SteveD
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Joined: Tue Aug 03, 2010 3:29 am
Location: Melbourne, Oz.

Re: ´strange´running problem?

Post by SteveD »

What was the last work done on the bike?

Could be a few things. My first thought was holed diaphragms. Second was inadequate fuel mixture/supply. That could mean anything from blocked air filter, blocked air intake, blocked oem inside the tap fuel filters, blocked aftermarket inline fuel filters, blocked main jet/s....
Cheers, Steve
Victoria, S.E.Oz.


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PAS
Posts: 163
Joined: Sun Apr 06, 2014 10:52 am

Re: ´strange´running problem?

Post by PAS »

Loosen the gas cap and try it.
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